Process for removal of complex high molecular weight aromatic constituents from high boiling oils



Patented June 15, 1954 UNITED STATES PATENT OFFICE 2,681,301 PROCESS FOR REMOVAL OF COMPLEX HIGH MOLECULAR WEIGHT AROMATIC CON- STITUENTS FROM HIGH BOILING OILS Andrew F. Sayko and D N. J., assignors to S avid W. Young, tandard Oil Development Westfield,

Company, a corporation of Delaware Application October 1, 1951,

6 Claims. (Cl. 196-14.11)

ous temperatures and pressures are employed, as well as, various solvent to oil ratios. It is also known in the art to use various processes for the preparation of high quality heating oils by with a halogen compound preferably at elevated temperatures followed by contacting the same with a solvent, as for example, a light hydrocarbon solvent containing from about 3 to 8 carbon atoms in the The process of the Referring specifically to the drawing, a feed 1s removed from zone Serial No. 249,156

oil, as for example, a West Texas crude, is intro- Light hydrocarbon gases are removed overhead by means of line 3; a lower boiling hydrocarbon fraction is removed by means of line 4, a higher boiling hydrocarbon fraction is removed by means of line 5, and a somewhat higher boiling fraction is removed by to '700 F., preferably boiling in the range above 850 F., is segregated as a bottoms fraction by means of line 1. is to be understood that zone I may comprise any suitable number and arrangement of distillation zones or stages.

In accordance with the present invention, the

zone 9 by means of line IIJ wherein it is contacted with a halogen compound introduced into zone 9 by means of line II. Evolved gases are removed from zone S by means of line II2. It is to be understood that treating zone 9 likewise may comprise any suitable number and arrangement of stages.

The treated oil is withdrawn from zone 9 by means of line I3 and introduced into solvent or precipitation zone I4. The oil is contacted in zone I 4 with a suitable precipitation solvent which is introduced by means of line I5. Ternperature and pressure sired. Precipitation zone I4 may comprise any suitable number and arrangement of stages.

-The treated oil free of undesirable high molecular weight highly aromatic type constituents I4 by means of line I'I and introduced into a solvent separation zone I 8 which may comprise a distillation zone. The solvent is removed `by means of line I9 while the treated oil free of solvent and undesirable constituents is removed by means of line 20. This oil may be removed from the system by means of line 2l and used as a heating oil or as a feed stock for various other processes which require that the oil be free or substantially free of high 3 molecular weight highly aromatic type constituents.

However, a preferred adaptation of the invention is to combine the foregoing with a catalytic cracking operation. As pointed out heretofore, the use of reduced crudes in a catalytic cracking operation has presented problems due to the fact that it has not been possible heretofore to remove high molecular weight highly aromatic constituents from these high boiling reduced crudes to a satisfactory extent. The presence of these constituents in a feed oil in a catalytic cracking operation causes excessive formation of carbon on the catalyst, thus substantiallydecreasing the activity of the catalyst. Therefore, in accord'- ance with a preferred adaptation of the `present invention, the treated oil removed by means of line'20 is introduced into zone 22 by means of line 23. .i

Temperature and pressure conditions in crack ing zone 22 areadjusted soas to secure the desiredA conversion. of the feed oil. Constituents boiling in the vapor phase are removed by means Ofiline 2d; constituents boiling in the motor fuel boiling range are removed by means of line 25 while higher boiling constituents are removed by means of line 20. A high boiling oil, as for example, acycle oil is removed by means of line 2lfand disposed of as desired. In accordance with apreferred adaptation of the present invention, at least a portion of this oil is recycled byrmeans ofy line 28 to the halogen compound treating zone. .Y

The invention isbroadly concerned withV the removal of high molecular weight and highly aromatic materials from petroleum oils, particularlyfrom petroleum oilsboiling in the reduced crude boiling range. Petroleum oils treated in accordance with the present invention are par-l ticularly adapted asY feed stocks for. a catalytic cracking reaction. Although the invention may be. adapted for the treatment of mineral oils boiling over wide ranges as pointed out above, it is particularly adapted for the treatment of oils boiling above about'lOO F., preferably boiling above about 860 F. Various halogenated compounds ployed, as for example,

CHzClz, CHCls, CI-laCClzl-I, Cl-IsCHzCCla, CHC1=CC12; CC12=CC12, CHzClCI-IzCl, CHzClCI-lClz, CHClzCCls, CClaCCla, CI-laCI-IClCHzCl Mixtures of compounds, as for example. `CCL; and ClCH2OC2H5 may also be used. Particularly. desirable treating agents comprise carbon tetra chloride and tetrachloroethane.

Pressures may vary from atmospheric to 1000 p. s. i. g., whilentemperatures are in the range from about 300 F. to 600 F. A preferred temperature range is from about 350 F. to 400 F. [Ijhe time of treatment may likewise vary appreciably depending upon the feed stock and upon the particular halogen treating agent utilized. YIt is preferred that the time of treatment be in the range of about 120 to 180` minutes. n K

Y The amount of halogen compound employed will depend upon other operatingY variables, as for example, temperature, pressure and the parmay be emticular halogen compound employed. 'Usually the amount employed is in the range from 1/2 to 10% by weight and a preferred amount is in tuhegrange from about 3 to 5% by weight, based upon the feed oil being treated.

`The particular precipitating solvent or solvent mixture employedin the precipitation zone may a catalytic cracking be selected from a Wide class of light hydrocarbon and low boiling oxygenated compounds, as for example, various ketones and the like. Desirable solvents comprise parainic hydrocarbons having from about 3 to 8 carbon atoms in the molecule, while the preferred solvents have 3 to 4 carbon atoms in the molecule. Temperatures utilized are in the range from about 50 F. to 150 F., while pressures vary from atmospheric to 1000 p.,s. i. g. The amount of solvent employed is usually in the range from about l to5 volumes of solvent or solvent mixture per volume of oil being treated.

' As discussed above, the invention is particularly` concerned with an improved operation which comprises the treatment of a reduced crude by` contacting it with a It is well known in the art to produce cracked naphthas byY a iiuidized solidsV catalytic operation wherein the cracked product comprises constituents boiling in the motor fuel boiling range, as forexample, below about 430 F. The cracked product also comprises normally gaseous constituents, as for example, those containing ythree carbon atoms and less Yin the molecule. The fluidized solids technique for processing feed fractions, as for example, gas oils, heavy residuums and other feed stocks for the production of hydrocarbon fractions boiling in the motor fuel boiling range is a conventional one. One system of a uidized solids technique comprises a reaction Zone anda regeneration zone, employed Vin conjunction `with'a fractionation zone. The reactor and the catalyst'regenerator are arranged at approximately an even level. The'operation of the reaction zone and the regeneration zone is. conventional, which preferably is as follows:

An overflow pan isprovided in the regeneration Zone at the desired catalyst level.v The catalyst overflows into a withdrawalline whichpreferably has the form of a U-shaped seal leg ,connecting the regeneration zone with the reaction zone. The feed stream introduced Yis usually preheated to a temperature in the range from about 500 to 650 in exchangers in heat exchange with regenerator ue gases which are removed overtiOll.

l, head from the regeneration zone, or with cracked products. The heated feed stream is withdrawn from the exchangers and introduced into the reactor. The seal leg is usually suiiiciently below the point of feed oil injection to prevent oil vapors from backing into the regenerator in case of normal surges. Since there is no restriction in the overflow line from the regenerator, satisfactory catalyst now will occur as long as the catalyst level in the reactor is slightly below the catalyst level in the regenerator when vessels are carried at about the same pressure. Spent catalyst from the reactor flows through 'a' second U-shaped seal leg from the bottom of the reactor into the bottom of the regenerator. The rate of catalyst flowis controlled by injecting some of the air into catalyst transfer line to the regenerator.

The pressure in the regenerator may be controlled at the desired level by a throttle valve in the. overhead line ,from the regenerator. Thus, the pressure in the regenerator may be controlled at any desired level by a throttle valve which may be operated, if desired, bya diierential'pressure controller. If the pressure differential between the two vessels is maintained ata minimum, the seal legsrwill prevent gases from passing from one halogen compound, prep cipitating a residue and utilizing the treated stock to secure an improved catalytic cracking opera- 'vessel into the other in the event that the catalyst flow in the legs should cease.

The reactor and the regenerator may be designed for high velocity operation involving linear supercial gas velocities of from about 2.5 to 4 feet per second. However, the superficial velocity of the upilowing gases may vary from about 1-5 and higher. Catalyst losses are minimized and substantially prevented in the reactor by the use of multiple stages of cyclone separators. The regeneration zone is provided with cyclone separators. These cyclone separators are usually from 2 to 3 and more stages.

Distributing grids may be employed in the reaction and regeneration zones. Operating temperatures and pressures may vary appreciably depending upon the feed stocks being processed and upon the products desired. Operating temperatures are, for example, in the range from about 800 to 1000o F., preferably about 850- 950 F., in the reaction zone. Elevated pressures may be employed, but in general pressures below 100 lbs. per sq. in. gauge are utilized. pressures generally in the range from 1 to 30 lbs. per sq. in. gauge are preferred. A catalyst sponding to a space velocity of 1 to 20 hour of feed per weight of catalyst is preferred ratio is 2 to 4. Catalyst to about 3 to 10, preferably about 6 to are used.

The catalytic materials weights per utilized. A oil ratios of 8 by weight used in the lluidized `catalyst cracking operation, in accordance with the present invention, are catalysts. These catalysts are oxides of metals. of groups II, III, IV and V of the periodic table. A preferred catalyst comprises silica-alumina wherein the weight per cent of the alumina is in the range from about to 20 Another preferred catalyst comprises silica-magnesium where the weight per cent of the magnesia is about 5% to 20%. These catalysts may also contain a third constituent, as for example, ThO'z, W03, M00, BeO, Bi2013, CdO, U03, B203, Sn02, FezOs, V205' MnO, CrzOa, C'aO, T1203, Mg0 and Ce203 present in the concentration from 0.05% to 0.5%. The size of the catalyst particles is usually below about 200 microns. Usually at least 50% of the catalyst has a micron size in the range from about 20-80. Under these conditions with the superficial velocities as given, a fluidized bed is maintained wherein the lower section of the reactor, a dense catalyst phase exists while in the upper area of the reactor a dispersed phase exists.

The above described operation as pointed out, has not been entirely satisfactory for cracking heavy oils such as a reduced crude due to excessive formation of carbon on the catalyst. However, by combining the halogen treating stage with the precipitation stage and the catalytic cracking stage, an improved operation results when using feed stocks of this character. The process of the present invention may be further understood by the following examples, further illustrating the same.

conventional cracking Example I In one operation a West Texas crude oil was distilled to secure a residuum which comprises about 16% of the original crude. This residuum was treated with normal heptane for two hours at a reux temperature using 5 volumes of normal heptane per volume of residuum.

The precipitate segregated was about 3% of the oil contacted.

holdup corre- Example II In another operation the identical feed oil was treated as described. The precipitate obtained was 3.6% based upon the oil contacted with the normal heptane. The precipitate and raffinate per cent Example III In a third operation the West Texas residuum was contacted with 5% by weight of carbon tetrachloride prior to contacting with normal heptane. The oil was contacted under reiiux with carbon tetrachloride at a temperature of 350 to 400 F. for a time period of minutes. The reaction was discontinued after no further hydrogen chlowith normal heptane as described The precipitate secured was 8.5% by weight. The

ratio with the precipitate secured in Example I. The precipitate and the rafnate had the following inspections:

Precipitate:

Carbon 83.14 Hydrogen 8.38 Chlorine 1.13 Hydrogen-carbon atomic ratio 1.21 Yield wt. per cent 8.5 Raninate Carbon 85.43 Hydrogen 11.55 Hydrogen-carbon atomic ratio 1.62

Example IV A 16% West Texas atmospheric residuum (200 grams) was treated with 10 grams of tetrachloroethane as described with respect to Example III. The formation of hydrogen chloride was noted at 380 F. Vigorous evolution of hydrogen chloride was obtained at 405 F. The reaction was completed after 21/2 hours with a maximum temperature or 450 F. The resultant residuum when treated with 5 volumes of normal heptane gave a yield of '7.3 weight percent of asphaltic precipitate. The analysis was as follows:

Per cent Carbon The tetrachloroethane treated residuum gives somewhat lower yields of asphalt, but still appreciably more than the untreated residuum. There is only a slight diierence in aromaticity and parainicity of the products from Example III and tetrachloroethane treatment as indicated by hydrogen-carbon atomic ratios.

The precipitate in Example III contains increased amounts of highly aromatic asphaltic materials not removable by the technique of Example II. The presence of 1.13 wt. percent chlorine in the asphalt results in increased melt- 4 The .raffinate from ing point and ductilitwvaszwell as in decreased penetration.

o Evxample III'having a slightlyhigher hydrogen-carbon atomic ratio is more lhighly' parafiinic. This results in an improved "cracking feed stock as compared to the raffinate aromatic constituents from a feed oil containing `the same which comprises treating said feed oil "iran vinitial stage at atemperature in the range from about 300 F. to 600 F. With a treating agent, consisting of a halogen compound selected from the class consisting of carbon tetrachloride andl tetrachloroethane, then contacting said oil in Va secondary stage with a precipitating light hydrocarbon solvent containing fromabout 3 to 8 carbon atoms in the molecule.

7 42. Process as defined by claim l wherein said feed oil boils in the range above about 700 F. Y 3, Process as dened by claim 1 wherein said halogen compound comprises carbon tetrachloride. l

4. Improved process for the production of hy- Y drocarbo'n constituents boiling intheV` motor ruel boiling range from a feed oil boiling above-'about 700 F. which comprises contacting said feed oil in an initial stage at a temperature in the range from about 300 F. to 600 F. With a treating agent consisting ofY a halogen compound selected from the class consisting oi carbon tetrachloride and tetrachloroethane, removing the oil and contacting the same in a secondary stage with a precipitating light hydrocarbon solvent having .from about 3 to 8 carbon atoms in the molecule,

separating the residue from the treated Voil and then contacting said oil with a suitable fiuidized cracking catalyst at elevated temperatures and pressures adapted to crack the oil and produce hydrocarbon constituents boiling in the motor fuel boiling range. Y

5. Process as deiined by claim 4 wherein the lfeed oil is an oil which boils above about 860 F.

6. Process as defined by claim i Whereinthe temperature utilized in said cracking zoneis above about 900 F. and wherein the pressure is below about 100 lbs. per square inch gauge.

References cited in the sie of this patent UNITED STATES PATENTS Number Name Y Date 2,045,806 Sloane June 30, 19,3 6 2,189,844 Starr et al. Feb. 13,1940 2,247,535 Voorhees July 1, 1941 2,378,762 Frey JuneAlQ, 1945 2,525,812 Lien et a1 Oct. 17, 1950 2,528,586 Ford Nov. 7, 1950 

1. IMPROVED PROCESS FOR THE REMOVAL OF HIGHLY AROMATIC CONSTITUENTS FROM A FEED OIL CONTAINING THE SAME WHICH COMPRISES TREATING SAID FEED OIL IN AN INITIAL STAGE AT A TEMPERATURE IN THE RANGE FROM ABOUT 300* F. TO 600* F. WITH A TREATING AGENT CONSISTING OF A HALOGEN COMPOUND SELECTED FROM THE CLASS CONSISTING OF CARBON TETRACHLORIDE AND TETRACHLOROETHANE, THEN CONTACTING SAID OIL IN A SECONDARY STAGE WITH A PRECIPITATING LIGHT HYDROCARBON SOLVENT CONTAINING FROM ABOUT 3 TO 8 CARBON ATOMS IN THE MOLECULE. 